The present invention is related to a combination marker/clearance lamp for vehicles, more particularly, a combination marker/clearance lamp for trucks or tractor-trailers.
Marker and clearance lamps are an important factor in the safe operation of trucks and trailers. These lamps make the vehicle more visible and detectable by other motorists, which effectively reduces the chances of collision.
A combination clearance and marker lamp should be able to indicate the overall width, height, and length of the vehicle. To accomplish this, the lamp must emit light over a wide range of angles.
In the past, combination marker/clearance lamps were made by high intensity incandescent bulbs. Combination marker/clearance lamps have also been made with light emitting diodes. Light emitting diodes have a relatively long service life. However, most light emitting diode designs require a large number of light emitting diodes and complicated optics or mirrors to provide the requisite intensity and spread of light. A large number of light emitting diodes creates problems with heat dissipation, thereby resulting in a more complicated lamp. For example, to achieve the desired distribution of light in these lamps, a reflective surface or mirror is required. In addition, some lamps have utilized segmented circuit boards with mounted light emitting diodes, or aimed light emitting diodes, to provide for different angles of light distribution. Reflective surfaces or mirrors add additional cost and at least one extra part to the lamp design. Segmented boards, on the other hand, usually require special mounting considerations and generally can not be potted for protection. The additional requirements of a segmented board construction make the construction of the lamp more complicated and potentially more fragile.
U.S. Pat. No.5,388,035 shows a circular lamp using only three light emitting diodes. Each of the light emitting diodes is aimed in a specific angle such that the conical light output beam is centered on an axis that is normal to the plane of the lens wall. The rear surface of the lens front wall contains three sets of light spreading prism ribs, which are optically aligned with each light emitting diode. This arrangement provides for an output beam whose width is about 30 degrees in the vertical plane and 90 degrees in the horizontal plane. There are some disadvantages to this design, including but not limited to the requirement that light emitting diodes must be aimed at the correct angle and aligned perfectly with the corresponding set of optics during construction of the lamp. The resultant lamp provides an output beam whose width is only about 30 degrees in the vertical plane and 90 degrees in the horizontal plane.
The subject invention overcomes these issues by using less complicated optics and, in one embodiment, a smaller number of light emitting diodes, which do not require complicated alignments with optics or reflective surfaces. In addition, the subject invention distributes light over a wide range, in particular from 0 degrees to 90 degrees. This increase in light distribution provides for a more visible and detectable lamp by other motorists.
The present invention solves the above mentioned limitations of the prior art in a cost-effective manner by using a more simple optics design and, in one embodiment, a reduced number of light emitting diodes which does not require a mirror to produce the light intensity and angular distribution desired for combination marker/clearance lamps.
The present invention eliminates the need for mirrors by making use of a process called total internal reflection (TIR). The embodiments of the subject invention utilize an optical system that comprises, among other things, one or more collimating lenses capable of TIR above a light source. The TIR optical system provides that each collimating lens is disposed under a conical shape lens optic. The optical system further comprises rib optics. The optical system concentrates and disseminates the light produced by the light source over angles ranging from 0 degrees to 90 degrees horizontally to each side of the lamp.
In the embodiments of the invention, the light source is at least one light emitting diode. The embodiments of the invention provide for a reduced number of light emitting diodes, i.e. the maximum number of light emitting diodes required would be approximately four, but the subject invention could potentially work with as little as one light emitting diode.
In the embodiment disclosed herein, one light emitting diode is positioned under each of the collimating lenses capable of TIR. The collimating lens is a convex lens that intercepts the cone of light produced by the light emitting diode and converts the light to a beam of parallel lights. The resultant parallel beams illuminate the conical depression at the center of the TIR optics system. Because the parallel beams of light hit the conical surface at an angle greater than the critical angle, the light is reflected from the lens surface rather than transmitted through the lens surface. As a result, the light is distributed in a substantially horizontal, radial pattern. Viewed from the front of the lamp, the embodiments disclosed herein include an elliptical shaped protrusion surrounding the conical depression. This elliptical protrusion acts as a lens, concentrating the light, which is being distributed radially from the conical depression, into a more directional beam in order to assure adequate intensity to the left and right of the lamp in a range of approximately 60 degrees to 90 degrees.
These above mentioned and other objects of the invention will become more apparent from the following description of the best mode for carrying out the invention.
Accordingly, it is an object of the invention to utilize a reduced number of optical elements to attain the desired directional light emission.
Additionally, it is an object of the present invention to provide a combination marker/clearance lamp that utilizes a reduced number of light emitting diodes.
It is also an object of the present invention to provide a combination marker/clearance lamp that utilizes total internal reflection (TIR) to distribute light over a wide range of angles.
It is a further object of the present invention to provide a combination marker/clearance lamp that utilizes an optics design that eliminates the use of reflective surfaces and segmented circuit boards to emit and distribute light.
In addition, it is an object of this invention to provide a unique optical system, using ribbed structures, a collimating lens and a conical depression.